Consider the dissolution of quartz (SiO2) in water at 25°C: SiO2(quartz) + 2H2O(l) ↔ H4SiO4(aq) If the solution equilibrates, what will be the dissolved concentration of H4SiO4? (Hint, use the thermodynamic data in the following table to calculate ΔG°r, then calculate Keq for the reaction)

Consider the dissolution of quartz (SiO₂) in water at 25°C:

SiO_2(quartz) + 2H₂O_(l) ↔ H₄SiO_4(aq)

If the solution equilibrates, what will be the dissolved concentration of H₄SiO₄? (Hint, use the thermodynamic data in the following table to calculate ΔG°r, then calculate Keq for the reaction).

                                    G°f (kJ mol^-1)               H°f (kJ mol^-1)

            SiO_2(Quartz)         -856.3                          -910.7

            H₄SiO_4(aq)          -1307.9                        -1457.3

            H₂O₍₁₎               -237.14                         -285.83

If the temperature of the solution is decreased to 15°C and the solution re-equilibrates with quartz, what will be the dissolved concentration of H₄SiO₄? Is the solubility of quartz higher or lower at colder temperatures?